66 



The introduction of Compositae with a pappus on the fruits is 

 by many authors on the new flora of Krakatao ascribed to direct 

 action of the wind and sometimes they add as a corroborating 

 argument the unlimited numbers Nature works with. One can, of 

 course, to a certain extent acknowledge the possibility of such a 

 transport, but when, as in the case of Krakatao, observations as well 

 as experiments are entirely Jacking, oecological and phytogeographical 

 problems cannot be solved by the acknowledgment and discussion 

 of probabilities. Not before it has been shown by irreproachable 

 experiments that seeds, fruits and fern-spores are directly transported 

 by wind to Krakatao from the surrounding islands or at least, that, 

 in such circumstances as prevail in the Sunda-straits, they might be 

 transported by wind that distance across the sea, one has some right 

 to take for granted that such a transport has really taken place. 



3. The most interesting fact is the occurrence of 1 1 ferns. Only 

 2 of these (Acrostic/mm aiireum I., and Nephralepis exa/tata Schott) 

 are \\idely dispersed in the islands of the hot regions '). Only for these 

 2 \vhich probably prefer a more or less saline substratum Krakatao 

 can ha\e offered some advantages in this respect. l~or the 9 other 

 species this is not the case. 



This is a rather vague conclusion. // is not true that but 2 of the 11 

 fern-species found by Freub are widely dispersed in the islands of 

 the hot regions; all of them, without exception, are quite common in 

 many localities of Java and Sumatra. One should bear in mind that 

 when Treub in 1888 wrote down this statement, the flora of the 

 hast Indian Archipelago and even that of Java was but very insuffi- 

 ciently known, especially as regards the distribution of the species. 

 The older collectors in the Dutch Indies, ) u n g h u h n excepted, 

 have applied themselves much more to discover new or rare species 

 than to get a survey of the local composition of the vegetation. 



Of the 2 supposed halophilous ferns mentioned by Treub only 

 Acrostichum aureum L. prefers a saline substratum, Nephrolepis exa/tata 

 Schott is halophobous. Seven of the I 1 ferns found in Krakatao in 

 1886 (No. 9, JO, 11, 12, 14, 15 and 17 of the list on PP . 61, 62) are 

 in Java and Sumatra common plants of unfertile soils. To these ferns 

 the basalt, pumice and young unweathered ashes of the investigated 

 part of Krakatao offered very favorable conditions of growth. 



l ) Ernst | Neue Flora Vulkaninsel Krakatau (1007), p. 7| somewhat inadequately 

 translates: ,,die mil 11 verschiedenen, im indomalayischen Oebiet weit verbreiteten 

 ,,Arten vertreten waren, unter denen aber nur zwei in der StranJfLira der Inseln vor- 

 ,,zukommen pflegen". This Treub did neither say noi mean. 



